Walking a “Fin”, as I discovered, was not
my favorite mode of travel. Most of the Fin was about five-foot wide,
except for those parts that were four-foot wide. I kept to the lee
side, where the drop down was only about twenty-five feet. To starboard
it was a sheer drop of 300-feet. The wind was up and kept buffeting
me to starboard.

We were on a 6-mile hike along the Devil's
Garden Trail at Arches National Park, Utah. I have no pictures of
the Fin we hiked on. The lead picture shows a Fin that we saw on
the Fiery Furnace Trail later that afternoon. It is a bit of an exaggeration,
since the Fin we hiked on started and ended on solid footing, but I felt
as unstable as the knob atop this one appears. Fins are created by erosion
and, as you will see, erosion is an essential theme of this story.

This is my second article about Hiking
with a Field Microscope. If you read my first one, you know I
see field microscopy as part of a total picture. That still goes.
What follows is a little geology, a little anthropology, a little natural
history, and even more about Cryptobiotic Soils.

A few things have changed. I have improved
my Swift FM 31 with the addition of a LazerBright
LED light. This very bright LED just fits the Swift microscope
and provides sufficient light for photomicrography for many weeks from
two tiny CR209 batteries!

I have also started using a Nikon
Coolpix 885 digital camera. The reference is to a review, since
the Nikon web site requires downloading software to see the camera.
I spent about 4-months choosing a digital camera. The choice of the
Coolpix 885 represented the smallest camera providing at least 3-megapixels
resolution, a small lens diameter, and sufficient optical zoom and digital
zoom to avoid vignetting.

One can shoot photomicrographs by holding
the camera to the microscope eyepiece. For convenience, I added a
used Leitz Wetzlar #519-815 Periplan GF 10X/20 eyepiece. This wide
field eyepiece has 28-mm threads that screw
directly into the attachment ring, enabling the camera to be securely
attached to the microscope. A variety
of other devices are available to attach digital cameras to a microscope
eyepiece. I have since tried a Canon 2.1-MP PowerShot S110 Digital
Elph, a Kodak DC 3400 200M Digital camera [2.0-MP], and an Olympus C-3020
Camedia [3.3-MP]. The first two performed well, but the lens on the
Olympus is much larger than the eyepiece lens and this results in vignetting.
For those who would like more information about the LED lights, about using
digital cameras, or about placing scale bars in digital photomicrographs,
Comments to the author sent via our contacts page quoting page url plus : ('wlanier','')">please
contact me.

The Colorado Plateau is geologically
and ecologically unique. It occupies a good part of the Four Corners
area, where the four square corners of Utah, Colorado, New Mexico, and
Arizona meet. It has been a single geological province for 500-million
years, much of that time under shallow seas [REF 1]. Most of its
strata are marine-deposited sandstone. The Triassic Navajo Sandstone,
2,500-ft thick, is one such sandstone. Another is the Entrada Sandstone.
Still showing the “petrified dunes” of their shallow-sea history, water
has eroded these formations from flat plateaus into Fins, Hoodos,
Towers, Knobs, Arches, Bridges, and caves. Most of the excitement
that produced the present-day exotic geology is water erosion that happened
so recently as to be coincident with human evolution.

Our trip was a two-week spring visit
to the US National Parks and Monuments
in Utah. We hiked in Arches, Canyonlands, Natural Bridges, Cedar
Mesa, Escalante Winding Staircase, Bryce Canyon, and Zion. We had
driven from San Francisco and this bit of roadside art in Nevada showed
how we felt coming back.

The spring flowers were out, those brilliant
desert plants that bloom the instant it rains [REF 2]. Many of the
animals were noticed by their leavings, which is why I carried my “Scats
& Tracks” [REF 3]. We did see many lizards and one female wild
turkey.

We found a number of abandoned cliff dwellings.
Over a span of 8,000-years the “ancestors” [called “Anasazi” by the Navajo]
built stone houses and lived on flat-floored niches in the cliff faces
of canyons [REF 4]. Frequently they decorated vertical surfaces nearby
with petroglyphs, which may have served as warnings, religious symbols,
or simply “news”. Cliff dwellings and petroglyphs are found throughout
the Colorado Plateau. Wind, cold and water also shaped the ancestors’
life-style, forcing them to abandon the cliff dwellings during the 12th
century AD. In Utah, cliff dwellings are small and usually quite
old, but in Chaco
Canyon, New Mexico, the ancestors built a large central city with four-story
stone buildings and some 400-miles of paved road. My photograph of
Cliff Dwellings was taken in Cedar Mesa, and the photograph of petroglyphs
was taken at “News Rock”, near Canyonlands.

Cryptobiotic Soil crusts [REF 2] are
now recognized as playing an important
ecological
role in the cold, dry deserts of the Colorado Plateau. Shown
is a close-up of about a square-foot of mature Cryptobiotic Soil, mostly
sand. The dark areas are typical of well-developed crust, and the
lichens on the central clump of soil show maturity.

Although this soil community also contains
lichen and mosses, it is initiated by and dominated
by cyanobacteria. On the Colorado Plateau, the species of cyanobacteria
commonly found in cryptobiotic soil is Microcoleus vaginatus.

Scale bar 50 µm

Scale bar 50 µm

M. vaginatus is a large, filamentous
green cyanobacterium.
Each segment in a filament is an individual bacterium. Filaments
range considerably in length. Shown below is a short filament, but
I found some filaments as long as 300 µm.

Scale bar 50 µm

Cyanobacteria are photosynthetic and were
originally called “blue-green algae”. At one time they were studied
in botany departments, but got kicked over to the microbiology departments
when it was discovered they were actually bacteria. Many are motile,
but M. virginatus is not.

One of the more interesting and increasingly
accepted hypotheses of evolution is that chloroplasts, the photosynthetic
organelles of higher plants, were originally cyanobacteria [REF 5].
According to this hypothesis, some early eucaryotic cell ingested a cyanobacterium
and the two negotiated a mutualism that, in plant cells, has lasted to
this day.

In dry soil, M. vaginatus remains
dormant in a cryptobiotic [desiccated] state. When water is provided,
the bacterial filaments come out of dormancy and, given sunlight, begin
growing rapidly. I examined dry cryptobiotic sand and found no apparent
cyanobacterial filaments. When water was added, filaments were evident
within a matter of minutes.

Although the transition from a cryptobiotic
state to an actively growing state is rapid, achieving a cryptobiotic state
takes much longer and requires many physiological changes. The water
content of soil is high, even as it dries out. During desiccation,
it passes through a long phase during which the relative humidity of the
atmosphere in the spaces between the grains is near 99%. This triggers
the physiological changes that enable cryptobiotic organisms to survive
desiccation and cold.

As they grow, the bacterial filaments produce
a sticky mucilaginous polysaccharide sheath, usually covering a number
of filaments.

Scale bar 50 µm

This sticky mucilaginous sheath binds the
filaments to soil particles, producing a matrix that is sufficiently strong
to make the soil surface crusty. As the soil dries out, the filaments
return to a cryptobiotic state, and the sheath around them remains connected
to the soil grains, pulling the grains tightly together.

The binding quality of the cyanobacteria
is evident from the observation that the angle of repose for dry cryptobiotic
sand is much steeper than for ordinary dry sand, which is about 34°.
You can get a sense of this by examining the larger fragments in the picture
of cryptobiotic soil. The face of the dark mottled area to the right
of the lichen-dotted fragment was almost perpendicular. At many places
on the Colorado Plateau I saw large expanses of stable dry sand on slopes
as steep as 45°. This crust resists wind erosion and, to a great
extent, water erosion.

With time, fungi, algae, lichens, and mosses
join the community and it becomes an inviting place for colonization by
higher plants. Notice that the Claret Cup in the photograph near
the beginning of this article is growing on cryptobiotic soil. Cryptobiotic
soil is the first step in producing arable soils in a desert ecosystem,
playing an essential role in stabilizing desert soil and limiting erosion.
When dry, however, cryptobiotic soil is brittle and does not resist footprints.
Wind and water erosion follows quickly, once a careless hiker breaks the
crust. The shortest recovery time for such disturbed soil is in the
order of 5 years. A mature soil may take up to 50 years to form.

Photomicrographs of Microcoleus
vaginatus were made in the field at Arches National Park, Utah [N 38-deg
46.925' W109-deg 35.677'], on the Devils Garden Loop Trail near Landscape
Arch. A hiker had left the trail and disturbed an area of cryptobiotic
soil. Some of the cryptobiotic soil fragments had been kicked onto
the trail from the disturbed area. I placed few grains of this soil
onto a microscope slide and wet them with about 50-microliters of water.
Then I put a cover slip over the soil/water mixture and placed the slide
in a shady area for awhile before popping it under the microscope.

After observation and photographing, the
contents of the slide were washed back onto the soil near the trail.
The National Park rules require that “nothing be taken out” and that you
leave intact cryptobiotic soil crust undisturbed. If you want to
observe the life in cryptobiotic soil, sample from the trail where hikers
are already walking. If you want to keep a sample for extended observation,
collect it outside the National Park areas [almost all sandy soil anywhere
in the Colorado Plateau develops cryptobiotic crust].

My observations were made over a period of
about 30-minutes, at 40X, 100X, 400X, and 800X under both brightfield and
phase contrast. Photomicrographs were taken at 400X bright field
using my Nikon Coolpix 885 digital camera, with full optical zoom and either
no “electronic zoom” or 2.0X electronic zoom. About half the full
optical zoom was necessary to prevent vignetting, but intermediate values
of optical zoom are not calibrated and I found it simpler to always use
the full value.

In conclusion, one could easily spend
a lifetime of vacations hiking the various parts of the Colorado Plateau
and observing the many ways life has adapted to its harsh conditions.
Everywhere, life struggles against the erosion that promises to wear the
high plateau down to a low plain.

Perhaps the most fascinating of these other
communities were ephemeral pools: Shallow sandy-bottomed depressions in
the rim rock above the canyons. I tried to photograph the Whiptail
lizard shown earlier as it paused in such a depression, but it hurried
on to bare rock. A microscopic examination of the dry sand from one
of these depressions shows only a few diatom skeletons. Such depressions
fill with water after a rain, and from the sand explodes a community of
microbes: Cyanobacteria of many kinds, diatoms, algae, fungi, lichens,
protozoa, rotifers, nematodes, and higher creatures that have found ways
of surviving periods of intense cold, heat, and desiccation. Some
produce resistant spores or other propagules, some enter directly into
cryptobiotic states, but all are equipped to rapidly return to active metabolism
when the rains come and all complete a life cycle with the metronome ticking
at “presto”. In the photomicrograph above, green cyanobacteria were
apparent within minutes of adding 100-microliters of water to a little
dry sand in a depression slide. In less than an hour, these motile
cells were dividing and moving at their slow and stately pace!

[1] Fran A. Barnes (2000) Canyon
Country Geology for the Layman and Rockhound: A guide to understanding
the unique and spectacular geology of the canyon country of southeastern
Utah and vicinity, with a special section on rockhounding. Arch Hunter
Books, Thompson Springs, UT. 160-pp. $12.95.